Grounding device in an electrical connector



Sept. 9, 1969 R. 1'. SYLVESTER GROUNDING DEVICE IN AN ELECTRICALCONNECTOR Filed Jan. 12. 1968 Robert 'IZSylves'rer INVENTOR.

United States Patent 3,466,590 GROUNDING DEVICE IN AN ELECTRICALCONNECTOR Robert T. Sylvester, Albuquerque, N. Mex., assignor to theUnited States of America as represented by the United States AtomicEnergy Commission Filed Jan. 12, 1968, Ser. No. 697,508 Int. Cl. H01r3/04, 13/46 U.S. Cl. 339-14 3 Claims ABSTRACT OF THE DISCLOSURE Anelectrical connector with contact elements having in the periphery of afirst mating portion shell an annular groove with overlying marginallips and an annular grounding spring retained in the groove by edgesunderlying the groove lips, the grounding springhaving an arcuateintermediate section outwardly maintaining the underlying edges andextending beyond the periphery of the first mating portion shell forelectrical contact with a second mating portion prior to engagement ofthe contact elements.

Background of invention Electrical connections for couplingmulticonductor cables generally include plug and receptable matinghalves or portions with generally centrally located primary contactingelements and an elecrically conductive outer shell for shielding orgrounding. The conductive shell around the plug portion may be abarrel-like member which insulatively contains the primary contactingelements, and

fits into or mates with an annular groove between the receptacle outerconductive shell and an insulative insert carrying mating primarycontacting elements. The accepted manufacturing tolerances for the plugand receptacle shells are such that the outer periphery of the plugconductive shell may vary from the inner periphery of the receptableshell by a few thousandths of an inch. Thus the plug conductive shellmay be first received in the receptable shell in a loosely fittingmanner providing poor grounding and shielding through the connectorbody. In some circumstances a loose fit may not be detrimental tocircuit operaion, but where an electromagnetic field is present, such asfrom radar which produces radio frequency energy, a difference ofelectrical potential may exist between circuit components within thefield. Thus when the plug and receptacle portions are mated there may bea discharge or are between the principal contacting elements which maydamage or affect the connected circuitry if the outer conductive shellsare not first adequately grounded together.

Prior attempts to adequately ground a connector have included groundingelements welded, soldered, crimped, etc. to one connector half forcontacting the second mating half. There prior devices have in someinstances been used at relatively low temperatures because welded andsoldered joints may tend to weaken and possibly fail at elevatedtemperatures and a crimped joint could possibly loosen on thermalexpansion of its constituent parts. Further problems arose when itbecame desirable to produce connectors of materials such as aluminumwhich are difficult to weld or solder. These prior devices have beensubject to the objection that means, such as keys and keyways, providedto align or orient the primary contacting elements could interfere withor interrupt the grounding elements such that inferior shielding orgrounding would result if a large number of such as keys and keywayswere required.

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Summary of invention Therefore it is an object of this invention toprovide anew and improved grounding element in an electrical connector.

It is a further object to provide a grounding device which nearlycompletely encompasses the principal contacting elements and is normallywiped clean with each connection operation.

Various other objects and advantages will become apparent from thefollowing description of one embodiment'of the invention.

As shown, the invention is a grounding device for use in an electricalconnector having mating primary contacting elements insulativelyencompassed by conductive shells with slideably mafing surfacescomprising a continuous groove circumscribing a mating surface of one ofsaid electrically conductive shells said groove having an intermediateraised surface bounded by continuous spaced apart marginal lipsoverlaying a recessed bearing portion of said groove, a generallyannular grounding spring retained in said groove by said marginal lipshaving an intermediate arcuate section extending beyond the surface ofsaid conductive shell for electrically connecting a mating connectorhalf, the outer margins of said grounding spring electrically contactingand bearing on the outer margins of said recessed bearing portion ofsaid groove underlying said marginal lips and said arcuate intermediatesection supported by said intermediate raised portion of said groovewhen connected to a mating connector half.

Description of drawings FIG. 1 is a partially cutaway view of anelectrical connector half embodying the present invention and a typicalmating connector half.

FIG. 2 is a cross-sectional View of an electrical connector half of FIG.1 along line 2-2.

FIG. 3 is an enlarged sectional fragmentary view showing in greaterdetail a grounding spring segment.

Detailed description One embodiment of the present invention isillustrated in FIGS. 1 and 2 wherein an electrical connector plugportion 11 incorporating the present invention is shown aligned with amating socket or receptacle 13. The plug portion 11 includes anelectrically conductive shell or barrel section 15 which may slideablymate or fit along outer surface 16 into an electrically conductivereceptacle shell or hollow portion 21 along a corresponding innersurface 22 of the receptacle 13. An insulated insert or core 27 may begenerally centrally disposed within the recep tacle shell 21 butradially spaced from a portion thereof to form an annular groove 20 forreceiving barrel section 15. Insert 27 may carry one or more primaryelectrical contacts 31 which may mate with corresponding primarycontacts 29 carried by a generally centrally disposed insulated insertor core 25 within barrel section 15. The conacis 31 are shown as socketsin receptacle portion 13 for receiving contacts 29 shown as pins in plugportion 11, but it will be clear that this arrangement may be reversedor other known types of mating contacts may be used.

The barrel section 15, as shown, may include conventional contactaligning means, such as axially extending keys 17 extending radiallyfrom surface 16 which align with cooperating axially extending keyways19 formed within the surface 22 of the mating receptacle 13 to properlyorient the primary contacts. The keys and keyways may be provided oneither the plug or receptacle or in mixed combinations thereof extendingin either straight or helical paths depending on the desired operation.

An outwardly extending peripheral shoulder or ridge 23 may be formed onbarrel section at a suitable longitudinal location to limit thepenetration of the barrel section 15 into receptacle shell 21 and groove20. Secure connection between the plug and receptacle portions may beprovided by a threaded collar or coupling ring 39 having an inwardlyextending flange which abuts shoulder 23 and which may threadably engagea correspondingly threaded surface 41 on receptacle portion 13. Both theplug and receptacle portions may also include a threaded surface such as33 and 35 for facilitating engagement of an electrical cable having aplurality of conductors to the connector portions with the conductorssuitably connected to contacts 29 and 31.

A continuous recessed surface or groove 37 may be formed or machined ina suitable manner known in the art in the surface 16 about the peripheryor perimeter of electrically conductive shell or barrel section 15.Recess or groove 37 may be cut or continued through keys 17, whichextend radially outwards from the surface 16 of the barrel section 15,without interfering with the contact orientation function of the keys.Groove 37 may have passages or slots 43 which serve as load bearingportions (shown in greater detail in FIG. 3) undercut below theperipheral or outer surface 16 of barrel section 15 to provide a pair ofcontinuous overlying flanges or lip portions 45 along each side ofgroove 37. Intermediate and protruding radially outwardly beyond thebearing ortions of slots 43 in groove 37, may be a raised portion orgrounding spring support surface 47 which remains recessed below theouter surface of barrel section 15. The raised portion 47 may smoothlyrise outwardly from the margins 43 with generally obtuse angles orcurves so as to provide a form maintaining support for the overlyinggrounding spring to be described below.

The grounding spring or element 49 may be formed of electricallyconductive flat spring material or stock having a width less than thewidth of the recessed surface 37, but in excess of the width separatingoverlying lip portions 45. The flat spring material may be contouredwidthwise to form a curved, hereinafter referred to for convenience asarcuate, intermediate section 51 bounded by marginal or edge bearingsections 55. Transverse or widthwise slots 53 may be cut generallytransversely across the arcuate section 51 and terminating at or in themarginal sections 55 but stopping short of the distal or terminal edgesof the grounding spring 49. Slots 53 may be longitudinally spaced apartalong the grounding spring 49 to provide a plurality of arcuate springsegments (FIG. 1) between the slots to render the grounding springflexible for shaping into a desired configuration around the peripheryof barrel section 15 such as the annular configuration shown in FIG. 2.Arcuate intermediate section 51 may be initially shaped by conventionalcold pressing or other means or later deformed inwardly along marginalsections when the grounding spring 49 is assembled into recessed groove37. After assembly, the grounding spring 49 may be formed or reformed ina suitable manner, such as by rolling with radially inward pressure onthe arcuate intermediate section 51 to expand the grounding springsrelaxed width to exceed the distance or width separating lip portions 45and thus lock or retain the spring 49 within groove 37 The arcuateintermediate section 51 of the grounding spring 49 may extend radiallybeyond or above the external surface or periphery of barrel section 15and beyond the circumference of surface 22 of shell 21, as shown. Thegrounding spring may overlie the intermediate raised portion 47 of therecessed groove 37 so that when grounding spring 49 is constricted bypressure against surface 22 of shell 21, the raised portion 47 mayprovide support and a spring flexure limit for the arcuate intermediatesection 51. The distal edges of marginal or edge bearing sections 55 ofthe grounding spring 49 may be spaced from the distal edges of themarginal bearing portions 43 of recessed surface 37 such that thesedistal edges will not abut and limit constriction of the spring. Thelength or perimeter of the grounding spring 49 may be slightly less thanthe circumference or perimeter of the recessed groove 37 so that a smallgap 52 (FIG. 2) may be provided between the ends of grounding spring 49retained in groove 37 to allow for a shorter perimeter or constrictionof the spring.

When the plug 11 and receptacle portions 13 are mated the peripheralinternal surface 22 of the receptacle shell 21 may wipe across andconstrict radially inward the portion of the arcuate intermediatesection 51 extending above the peripheral surface of barrel section 15.The marginal edges 55 of the grounding spring 49 will consequently bearagainst and across the bearing portion of the slots 43 in groove 37making good, clean electrical contact there-with in a wiping or sweepingmotion. The arcuate section 51 resists flexure and constrictionestablish a firm and clean electrical connection between the barrelsection 15 and the receptacle shell 21 through grounding spring 49.

The grounding spring 49, barrel section 15, and receptacle shell 21 maybe composed of electrically conductive materials such as copper,beryllium, aluminum or silver, and may be cadmium plated if an improvedelectrical contact surface is desired especially on connector partscomposed of such as aluminum which normally may be coated with aninsulative aluminum oxide film.

Even though the connector components have been shown in an annularconfiguration, any closed or nearly closed configuration may be used.Also, the grounding spring 49 and retaining groove 37 have been shown aspart of the plug portion 11 on the external surface of the barrel member15, however it will be clear that the grounding spring may be made apart of the receptacle portion 13 such as at the inside surface orperimeter 22 of the receptacle shell 21. In the latter configuration, itmay desirable to position the keys on shell 21 rather than on barrelmember 15 so as not to interfere with the operation of the key andkeyway aligning means.

The invention provides an electrical connector having a new and improvedgrounding device. By providing grounding contact between the plug andreceptacle shells prior to mating of the primary contact elements anyelectromagnetically induced potential on any portion of the connectingcircuitry may be equalized without discharge or damage to the circuit.The grounding spring almost completely encompasses the connectorcircumference to maximize grounding contact, minimize possibility ofarcing at ungrounded points on the connector periphery during thecoupling operation and provide an encompassing electromagnetic shieldabout the primary contacts after the connector halves are assembled. Thegrounding spring is mechanically connected to the connector shell bylocking its edges under overlying lips of a peripheral groove. Thisconstruction provides a ground ing shield suitable for a high and broadtemperature ranges as there are no solder or weld joints to weaken athigh temperature or crimped joints to fail on material expansion. Byproviding a raised portion beneath the grounding spring, it may not beunnecessarily stressed when constricted and may consequently have a longlife. Furthermore the grounding device of this invention is especiallyuseful with aluminum connectors which are difficult to weld or solder.

By disposing the keys for orienting the primary contacts only on theconnector half having the grounding spring and recessed surface of thepresent invention, and disposing the mating keyways only on the othertypical connector half, the grounding springs need not be interruptedbut may pass through gaps formed in the keys allowing a large number ofalignment keys to be used without breaking the continuity of thegrounding spring.

It will be understood that various changes in the details,

materials and arrangements of the parts may be made by those skilled inthe art within the scope of the invention.

What is claimed is:

1. In an electrical connector mating portion having a contacting elementand an annular electrically conducting shell encircling said element andinsulatively spaced therefrom, a continuous recessed surface disposedabout a periphery of said shell having an intermediate raised portionbounded by a pair of continuous spaced apart undercut bearing portionswith each of said undercut bearing portions overlaid by a continuous lipportion, spring means coextensive with said continuous recessed surfacehaving an arcuate intermediate section overlying but spaced from saidraised portion and bounded by a pair of spaced apart bearing sections,the width of said spring means being normally less than that of saidrecessed surface whereby distal margins of the bearing sections arenormally spaced from distal margins of the hearing portions, saidsections projecting beneath said. lip portions and resting against saidbearing portions, said arcuate section having a plurality of oftransversely extending spaced apart slots throughout the length of thespring means and said arcuate section projecting beyond adjacentsurfaces of said shell, said raised portion of the recessed surfaceserving to support the arcuate intermediate section of the spring meansupon suflicient constriction thereof.

2. The electrical connector mating portion of claim 1 wherein there isprovided a raised alignment key on said periphery of said shell, saidkey having a first section axially extending away from said recessedsurface from one of said lip portions and a second section axiallyextending away from said recessed surface from the other of said lipportions.

3. The-electrical connector mating portion of claim 1 wherein saidconducting shell is composed of aluminum and there is provided a cadmiumcoating on said shell and said spring means.

References Cited UNITED STATES PATENTS 3,128,138 4/1964 Noschese 339-143,136,593 8/1964 Ehrman et a1 339-14 X RICHARD E. MOORE, PrimaryExaminer US. Cl. X.R.

